INCREASED SECRETION OF CHOLESTERYL ESTER TRANSFER PROTEIN FROM HAMSTER ADIPOSE-TISSUE - STIMULATION BY BETA-ADRENERGIC AGENTS

High levels of cholesteryl ester transfer protein (CETP) favours decre ased plasma high density lipoprotein cholesterol and increased levels of cholesterol in apolipoprotein B containing lipoproteins. Adipose ti ssue is one of the major sources of circulating CETP. Previous studies by our group and others demonstrated that the production of CETP from hamster adipose tissue increases after fasting, a metabolic state kno wn to affect the sympathoadrenal axis. The present study examines the influence of beta-adrenergic agonists on the secretion of CETP from ha mster adipose tissue. Fifteen minutes after an intraperitoneal injecti on of isoproterenol (12 mu g/kg), the release of CETP mass and activit y from adipose tissue fragments incubated in vitro were significantly increased. This was associated with an elevation in CETP mass and acti vity in plasma. The effects of isoproterenol on CETP release from adip ose tissue and plasma CETP levels were suppressed by propranolol, a be ta-adrenoceptor inhibitor. Addition of 10(-6) M isoproterenol to adipo se tissue in vitro increased the release of CETP mass and activity fro m adipose tissue and this was also blocked by propranolol. Isoproteren ol-induced secretion of CETP activity from adipose tissue was partiall y inhibited by cytochalasin B, an inhibitor of actin cytoskeleton reor ganization. Forskolin, a classical adenylate cyclase agonist and 8-bro mo-cAMP, a functional analogue of cAMP, mimicked the effect of isoprot erenol on CETP release from adipose tissue. Our results suggest that i soproterenol increases the secretion of CETP from hamster adipose tiss ue through a beta-adrenoceptor and a cAMP-dependent. pathway. Actin cy toskeleton reorganization may be required for secretion of CETP. The f indings imply that the secretion of CETP from adipose tissue is under neurosympathetic control. (C) 1998 Elsevier Science Ireland Ltd. All r ights reserved.